Discrete element analysis of dry granular flow impact on slit dams
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Sixia Gong I Tao Zhao I Jidong Zhao I Feng Dai I Gordon G. D. Zhou
Discrete element analysis of dry granular flow impact on slit dams
Abstract Slit dam is an open-check barrier structure widely used in mountainous regions to resist the destructive impacts of granular flows. To examine the dynamics of granular flow impact on slit dams, a numerical study by discrete element method (DEM) is presented in this article. The study considers dry granular materials flowing down a flume channel and interacts with slit dams installed at the lower section of the flume. The particle shape is explicitly considered by particle clumps of various aspect ratios. The slit dams are modeled as rigid and smooth rectangular prisms uniformly spaced at in the flume. Four key stages of granular flow impact on the slit dams have been identified, namely, the frontal impact, run up, pile up, and static deposition stages. In the impact process, the kinetic energy of the granular flow is dissipated primarily by interparticle friction and damping. The trapping efficiency of the slit dams decreases exponentially with the relative post spacing, while it increases with the particle clump aspect ratio. The numerical results can provide new insights into the optimization of relative post spacing for slit dam design. Keywords Dry granular flow . Slit dam . Discrete element method . Particle clump . Trapping efficiency Introduction As one of the common geological hazards, granular flow can significantly threaten human lives, structures and infrastructures, and lifeline facilities worldwide due to its fast-moving velocity, long runout distance, and high impact force (Chen et al. 2015; Hürlimann et al. 2006; Iverson 1997). Common mitigation measures are based on structural countermeasures to granular flow impacts, such as flexible barriers (Li and Zhao 2018), rigid obstacles (Teufelsbauer et al. 2011), and baffle arrays (Choi et al. 2018). As one of the most popular measures, closed check dam has the major drawback of being easily filled up by sediments due to relatively low storage capability and poor permeability (Cucchiaro et al. 2019). Failure of closed check dam may cause more devastating sediment-related secondary disasters, such as floods and debris flows. Alternative open-form barrier structures, such as slit dams and flexible barriers, have gained increasing favors in engineering practice (Choi et al. 2019; Choi et al. 2018; Zhou et al. 2019). A slit dam usually consists of an array of densely spaced concrete columns. These columns may serve as effective measures to dissipate the impact energy of granular flow and collectively help to retain a certain portion of coarse solids (Cui et al. 2018). It can thus control the peak granular discharge by allowing a relatively small portion of debris materials to pass through the slits. This approach may significantly reduce the destructive power of granular flow and thus the possibility of dam failure (Goodwin and Choi 2020). The performance of slit dam is influenced primarily by the so-called relative po
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